IMAP SMTP Send Server

Hello, Im using evolution and i have a school email (student.ednet.ns.ca) that i like checking in there, i have set it up to use IMAP as receiving/moving and SMTP for sending, but the SMTP keeps trying to send through my personal server (eastlink.ca). and thus doesnt pass authentication and wont send :(
there doesnt seem to be an option to change this, atleast none i saw. help

there is an SMTP server at the school, but when i use my school account on my computer through evolution it tries sending the mail through another server I use for SMTP, which wont pass its authentication, the reason I don't just modify it to use that other server is because that server is for my anonymous mail, and I don't want the school to know i have an account on that server...

if i use the alternative option, what do i put in place of <home_machine>?
its giving me: ssh: //xsanf: Name or service not known
when i put : sudo ssh -L:25:smtp.student.ednet.ns.ca:25 //xsanf

The "sudo ssh" line is typed into a terminal window each time you log into the machine. It is basically a command that says, "when I try to use port 25, I actually want you to go through my home machine instead of that other eastlink machine."

The terminal can be found at: Applications -> Accessories -> Terminal.

Note that the # prompt means they are using the root user. In the sample command given by Alan, you use "sudo" to mean, "when I issue this command I am doing it as the root user." You will be prompted for your password (not the root password).